Log skidder with cab-controlled cable binder



Nov. 11, 1969 R. R. MICHAELSON ET AL 3,477,596

LOG SKIDDER WITH CAB-CONTROLLED CABLE BINDER Filed Nov. 23, 1966 2Sheets-Sheet l INVENTORS REYNQLD R. MiCHAELSON BYPHIUP E. LGTENDRIESSEATTORNEYS Nov. 11, 1969 R. R. MICHAELSON ET AL 3,477,596

LOG SKIDDER WITH CAB-CONTROLLED CABLE BINDER Filed Nov. 23, 1966 2Sheets-Sheet 2 INVENTORS R-EYNOLD R. MICHAELSON I PHILIP E. LGTENDRESSEI W I,

ATT'ORNEYS United States Patent US. Cl. 214-92 14 Claims ABSTRACT OF THEDISCLOSURE A log skidder is disclosed in which the seizing and releaseof loads is controlled from the cab. A cable from a hydraulic winch hasa large loop at the end thereof threaded through the tips ofhydraulically actuated tongs, hung from a boom which can swingdownwardly to lower the tongs over a log or group of logs. This movementdrapes around the intended load the length of cable spanning between thetips of the tongs. The tongs are then closed sufiiciently to engagelower surfaces of the load. The winch draws the cable in to draw thespanning length thereof taut around the load; the boom swings up toraise the engaged end of the load, and the vehicle moves to drag theload to the desired location, whereupon the load is dropped and theentire vehicle and gear freed therefrom simply by opening the tongs. Thetongs may be hydraulically swiveled to lie transversely of an intendedload, so that the vehicle need not approach it from a particular angle.For use as a conventional skidder, the tongs may be locked up in theboom, and the cable threaded through pulleys located high enough to liftthe log ends by cable pull. Contributing details are disclosed.

The invention of which this disclosure is offered for publicdissemination if adequate patent protection is available relates to logskidders. Vehicles called log skidders have long been used in the woodsin connection with lumbering operations for dragging logs or tree trunksfrom a point of felling to a point of further handling such as loadingon trucks.

In the past, most log skidders have dragged logs by a cable whichrequired considerable manual labor in applying the cable to the load andeventually in releasing the cable from the load. Various forms of tongsor grapples have been proposed, and some have been used, butdifficulties of application, and the possibility of slippage (or theprobability of slippage, if more than one log were to be towed) has keptsuch devices from being sufiiciently satisfactory to widely replace themore conventional manually applied type.

According to the present invention, a cable and tong grapple is providedwhich may be quickly applied by cab control and which is thoroughlydependable in its grip on the load, whether one log or several. At thesame time, for rare problems such as the inability of the vehicle toreach the load, the cable can be payed out over an elevated pulley inthe usual manner of conventional log skidders.

Additional objects and advantages of the invention will be apparent fromthe description and the drawings.

DESIGNATION OF FIGURES FIGURE 1 is a side elevation of the skidder ofthe present invention, showing in broken lines, the grapple lice beingapplied to a log, and in full lines, the log being drag ed. FIgICiURE 2is a plan view of the apparatus shown in FIGURE 3 is a fragmentary viewsimilar to that of FIG. 2 but showing the tongs swiveled to lietransversely of a log which has been approached from the side thereof;

FIGURE 4 is an end view of a log showing the grapple being applied toit;

FIGURE 5 is a view showing the tongs locked to the yoke to hold steadyan elevated pulley over which the cable has been drawn;

FIGURE 6 is a detailed sectional view along the line 6-6 of FIG. 5,showing the interlocking of the tongs to the yoke;

FIGURE 7 is a fragmentary view showing the use of the cable for firmlybinding a plurality of logs to be dragged; and

FIGURE 8 is a fragmentary sectional view taken approximately on the line88 of FIG. 5 through the swivel spindle, showing the normal ortransverse disposition of the tongs and stop lugs in full lines and indotted lines showing these parts swung ninety degrees to the limit ofmovement.

INTENT CLAUSE Although the following disclosure offered for publicdissemination is detailed to ensure adequacy and aid understanding, thisis not intended to prejudice that purpose of a patent which is to covereach new inventive concept therein no matter how others may laterdisguise it by variations in form or additions or further improvements.The claims at the end hereof are intended as the chief aid toward thispurpose, as it is these that meet the requirement of pointing out theparts, improvements, or combinations in which the inventive concepts arefound.

GENERAL DESCRIPTION Except for the features to be described in detail,this skidder may be of various forms and has been illustrated asincluding front-driven wheels 11, rear-driven wheels 12, a jack-knifingpivot 13*, steering cylinders 14 of which only one is shown, and a cab16.

According to the present invention, a yoke or boom 18 is pivoted at alow point 19 to chassis 21, and is actuated by a pair of hydrauliccylinders 22.

A grapple assembly 23 hangs by a universal joint 24, seen best in FIG.5. The universal joint 24 is suspended from the top of the yoke 18 by astub shaft 26, extending downwardly from a swiveling unit 27.

The grapple assembly 23 includes a rectangular frame 28 (FIGS. 1 and 4)to the lower portion of which a pair of tongs 29 are pivoted. Thesetongs are actuated in unison by hydraulic cylinders 31. A cable loop 32is usually secured by release coupling 17 to a main cable 33 wound onhydraulic winch 34.

The tong assembly 23 may be swung to position its tongs transversely ofa log by operation of a hydraulic motor 36 forming part of swivel unit27. The hydraulic motor is located in a protected position largelybehind and extending downwardly from the top of yoke 18, and isconnected by an enclosed chain drive, represented by 7 chain 35 in FIG.2, to swivel shaft 26..

3 GENERAL DESCRIPTION OF NORMAL OPERATION In operation, the skiddervehicle is backed up to be adjacent to one end of the log or logscomprising the intended load. Depending on the convenience and thelocation of a clear path, it may be backed up in the direction towardthe end of the log, as seen in FIGS. 1 and 2, or toward the side of thelog as seen in FIG. 3, or in any intermediate direction. The driver ofthe vehicle first operates the correct one of a bank of easilyaccessible control levers 38 to operate hydraulic motor 36 to turn thegrapple assembly 23 to position the tongs 29 transversely of the log,with the rear face of the tongs facing toward the far end of the log. Atthe same or substantially the same time, he may operate another of thecontrol levers 38 in the direction for operating hydraulic cylinders 31for opening tongs 29, to the position seen in FIG. 4. Then the driverwill operate a third of the levers 38 in the direction for actuatinghydraulic cylinders 22 to swing the yoke 18 (and grapple assembly)rearwardly and downwardly to the position shown in broken lines in FIG.1, with the intervening cable portion 39 draped over the load.

Next, the operator will operate the tong control lever in the oppositedirection to close the tongs 29 so that they grip the lower surfaces ofthe load, somewhat as seen in FIG. 7. They may either wedge themselvesunder the load as seen in FIG. 7, or merely engage the downwardly facingside portion of the load as seen in full lines in FIG. 1. Unless theload looks precarious, the driver will raise the boom at this time.Before or after raising the boom, the driver will operate still anotherof the levers 38 to actuate hydraulic winch 34 in the winding direction,pulling in cable 33. This causes cable loop 32 to slip through the tipsof tongs 29 and tighten the intervening cable portion 39 about the load.This combined action of the tongs and cable has been found to beextremely reliable, even with the difficult load of a multiple of logsas seen in FIG. 7.

Unless he did so previously, the driver now operates the boom controllever 38 in the opposite direction to raise the boom 18 and with itraise the firmly gripped end of the load. The grapple unit 23 may assumea sloping position in this operation, since friction of the logs on theground will resist the tendency of the grapple unit 23 to hang down to avertical position. However, the driver will preferably operate hydraulicwinch 34 again to pull in more cable 33 until grapple unit 23 isapproximately vertical, so that the entire pulling force exerted on thelog will be derived through cable 33. This pulling force incidentallymaintains adequate binding tension on intervening cable portion 39. Thedriver now drives the vehicle, with all the hydraulic control levers 38in the neutral or hydraulic lock position so that the load is held inthe relative position shown in FIG. 1 and dragged or skidded by movementof the vehicle.

When the driver has skidded the log to the desired location, he canmerely operate the lever in bank 38 which controls tongs 29 to open thetongs 29, whereupon the log will drop free, and all of the parts will beconditioned for the skidder vehicle to move away. If the movement to thenext load to be skidded requires substantial travel, especially overrough terrain it is preferred the tongs 29 be locked in yoke 18, asdescribed below, so that they will not swing and cause damage.

When pulling the log on a sharp turn or the like, the drag of the logtends to swing the grapple assembly 23 toward one side. To guard againstexcessive movement of this type, and to keep the cable extendingrearwardly from the winch, guide rollers 41 are provided at the rear ofchassis 21. Preferably, they are sloped with their upper ends rearwardlywith respect to their lower ends, so that the cable will tend to passthrough them in a direction perpendicular to their common axial plane.There may also be upper and lower pulleys 42 and 43,

4 USE AS CONVENTIONAL SKIDDER When the skidder vehicle cannot approach aload closely enough for engaging it with the grapple assembly 23, theskidder of this invention can quickly be converted to a conventionaltype of skidder. This is accomplished by spreading apart the tongs 29 tointerlock in yoke 18 as seen in FIGS. 5 and 6, and threading the cable33 over upper pulley 44 and between guide rollers 46. Usually in thiscase the cable loop 32 will be released from main cable 33 by operationof a quick release coupling 47. The main cable 33 can then be pulled out(driving hydraulic winch 34 in a paying-out direction) to theinaccessible load, where it is attached to the load in the conventionalmanner. Then the winch 34 can be operated in the drawing-in direction,drawing the load into adjacency to the vehicle, whereupon the vehiclecan be driven to skid the log to its desired destination, and the cablemanually released from it.

The interlocking of tongs 29with yoke 18 is easily accomplished. It ismerely necessary to spread apart the tongs 29 after aligning them withyoke 18 either by drawing cable 33 or by swinging yoke 18 to thevertical position, which may be at the limit of its movement in theforward direction. The transversely disposed tongs will then be alignedwith a recess for their reception formed between rear plate 51 and frontplate 52, both welded to yoke 18. Rear plate 51 has been illustrated asextending beyond front plate 52 so that if desired, the tongs can bepositioned to swing rearwardly between the two plates 52 and stillstrike the plates 51.

FURTHER DISCLOSURE The upper section of universal joint 24 carries stoplugs 56 and 57 which strike fixed stop 58 carried by housing 59 ofswivel shaft 26 to limit the swivel action. At present the limit is atthe ninety degree position in each direction from normal. FIG. 8 showsin dotted lines stop lug 56 engaging stop 58. Others may prefer a littlemore than ninety degrees. The only need is to avoid interference of thetongs 29 with the cable (especially as it is drawn in) and to avoidexcessive twisting of hoses, not shown, running to cylinders 31.

The universal joint 24 need not be of the sophisticated type shown. Twolinks of chain or linked eyes can serve reasonably well. If less perfectuse of the invention is desired for economy, and the hydraulic swivelingis omitted, a simple, swivel, or a spring-centered swivel may be used.

The loop 32 should be very flexible cable, wire rope or the like.Although it suffers considerable wear, it is a short enough piece to bereplaced at low cost. It should be long enough, however, to receive anyload tongs 29 can receive. The apertures for it through the tongs shouldbe rounded for easy sliding, and may comprise frictionreducingreplaceable inserts.

The grapple 23 is preferably painted differently on different sides sothat when longitudinally aligned, the operator will know, withoutremembering, the direction of lever movement which will restore it tonormal.

ACHIEVEMENT It is readily apparent from the foregoing description that askidder of exceptional convenience, dependability and efficiency hasbeen provided. When the skidder can reach the load, all of thefatiguing, costly, and time consuming hand labor for securing the dragcable to the load can be avoided. Very quickly, the operator, 'byhydraulic controls operated from the drivers seat, can apply the grappleunit to the load, securing the load with extreme dependability, andraise the secured end of the load to a position for optimum ease ofskidding. Upon reaching the destination, a single hydraulic control atthe drivers seat releases the load so that the vehicle is free to moveaway for the next load. If preferred, the t ngs 29 may be lock d in yoke18 so that th y ill n t.

swing and cause damage. With such locking, the vehicle can also quicklyand easily be converted to a conventional skidder when conventionaloperation is necessary as when the vehicle cannot get to the load butmust winch it out of an inaccessible place. r

. With the preferred (grapple) operation, the more the load resistsmovement, the tighter it is bound. The greater pull on cable 34 producesgreater binding force on intervening portion 39 and tighter gripping bytongs 29, which are preferably providedwith sharp edges 66 (FIG. 5).Tips 67 are also moderately sharp, but having the tongs reach under theload is preferred. It is never necessary, however, to dig manually undera log, sometimes through snow or soil in which it is embedded, as inconventional skidder operation (where a cable must .be passed under alog). A non-wobbling grip is in any event ensured by phasing gearsegments 69 (FIG. 7).

No longer need an operator or other worker be exposed to such hazards asbroken limbs, due to falling logs or snapping cables, nor to poisonousplants or animalswhere they exist.

A further advantage is that the pull of the cable is at a much lowerpoint on thevehicle than on conventional skidders, contributing togreater stability and much improved safety.

Hydraulic motor 36 can be turned by chain 35, when a dragged log swingsin turning. This is permitted by cross-relief valve 71 (shownschematically in FIG. 2) there being no irreversible gearing. Also,because such forces are too great to restrain, stop 58 is a shear pinreadily replaced. It may be a bolt with a pair of lock nuts. It willshear ofi harmlessly (except for its own replacement in the field) iftongs 29 are applied wrong way about, in the FIG. 3 situation.

We claim:

1. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand includingelevating means and a grapple hung from the elevatingmeans, said elevating means and grapple being capable of elevating theleading end of an elongate load, characterized by:

power winchmeans on the vehicle, a cable leading therefrom to the lowerpart of the grapple to drag the load asthe vehicle moves and to adjustthe I I hanging angle of the grapple;

said grapple including tongs and a flexible binder intervening betweenthe lower portions of the tongs and drawn by the cable for tighteningabout the load in the tongs for skidding the load; and

control means accessible at the drivers position for controlling theelevating means and tongs and the Winch means; said elevating meansbeing operable independently of thewinch, cable and binder.

2. A skidder according to claim 1 including guide means for a cablesubstantially above the tongs, through which a cable can be payed out tobe manually engaged to a load spaced from the vehicle too far forengagement by the tongs and from which a lifting'component will bederived.

'3. A log skidder according to claim 1 including guide means for thecablenear the level of a raised load and additional guide means for thecable substantially higher, through which a cable can be payed out tobemanually engaged to a'load spaced from the vehicle 'too far forengagement by the tongs and from which a lifting component will bederived.

4. A skidder according to claim 1 in which the elevating means is a boomin the form of an inverted U with the tongs hingedly hanging from thetop of the boom, and means for locking the tongs with respect to thelegs of the U to prevent swinging of the tongs when no load is beingcarried by them.

5. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand. including elevating means and a grapple hung from the elevatingmeans, said elevating means and gapple being capable of elevating theleading end of an elongate load, characterized by:

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the gapp'le to drag the load as the vehicle moves and to adjustthe hanging angle of the grapple;

said grapple including tongs and a flexible binder intervening the lowerportions of the tongs for tightening about the load in the tongs forskidding the load; and

control means accessible at the drivers position for controlling theelevating means and tongs and the winch means; in which the elevatingmeans is a boom in the form of an inverted U with the tongs hingedlyhanging from the top of the boom, and means for locking the tongs withrespect to the legs of the U to prevent swinging of the tongs when noload is being carried by them, said locking means comprisinginterlocking means for providing interlocking engagement between thetongs and the legs of the U when the tongs are spread apart while saidinterlocking means are in alignment.

6. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including elevating means and tongs hung from the elevating means,said elevating means and tongs being capable of elevating the leadingend of an elongate load, characterized by:

self elevating means being'a boom in the form of an inverted U with thetongs hingedly hanging from the top of the boom, and means for lockingthe tongs with respect to the legs of the U to prevent swinging of thetongs when no load is being carried by them, said locking meanscomprising interlocking means for providing interlocking engagementbetween the tongs and the legs of the U when the tongs are spread apartwhile said interlocking means are in alignment.

7. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including a grapple, elevating means hanging the grapple therefrom,said elevating means and the grapple being capable of elevating theleading end of an elongate load, characterized by:

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the grapple independently of the means hanging the grapple todrag the load as the vehicle moves and to adjust the hanging angle ofthe grapple;

said grapple including tongs and a flexible binder freely passingthrough the tongs and intervening between the lower portions of thetongs and drawn by the cable for tightening about the load in the tongsin response to tension on the cable for skidding the load; and

control means accessible at the drivers position for controlling theelevating means and tongs and the winch means.

8. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including a grapple, elevating means having means hanging thegrapple therefrom, said elevating means and grapple being capable ofelevating the leading end of an elongate load, characterized by:

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the grapple independently of the means hanging the grapple todrag the load as the vehicle moves and to adjust the hanging angle ofthe grapple;

said grapple including tongs and a flexible binder intervening betweenthe lower portions of the tongs and drawn by the cable for tighteningabout the load in the tongs for skidding the load;

p'owered swiveling means forming part of the elevating and hanging meansfor swinging the tongs angularly about a generally vertical axis to liecrosswise of the elongate load when the vehicle is not aligned with theload length; and

control means accessible at the drivers position for controlling theelevating means and tongs and the winch means.

9. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including a grapple, elevating means having swivel means hanging thegrapple therefrom, said elevating means and grapple being capable ofelevating the leading end of an elongate load, characterized by:

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the grapple independently of hanging the grapple to drag theload as the vehicle moves and to adjust the hanging angle of thegrapple;

said grapple including tongs and a flexible binder freely passingthrough the tongs and intervening between the lower portions of thetongs and drawn by the cable for tightening about the load in the tongsin response to tension on the cable for skidding the load;

powered swiveling means forming part of the elevating means for swingingthe tongs angularly about a generally vertical axis to lie crosswise ofthe elon gate load when the vehicle is not aligned with the load length;and

means limiting the swivel movement of the swivel means to prevententanglement of the tongs and cable.

10. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including a grapple, elevating means including a boom pivoted at itslower forward end, means hanging the grapple from the upper rearwardportion of the boom, said elevating means and grapple being capable ofelevating the leading end of an elongate load, characterized by:

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the grapple independently of the means hanging the grapple todrag the load as the vehicle moves and to adjust the hanging angle ofthe grapple;

said grapple including tongs and a cable tensioned flexible binderintervening between the lower portions of the tongs for tightening aboutthe load in the tongs for skidding the load; and

control means accessible at the drivers position for controlling theelevating means and tongs and the winch means.

11. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including a grapple, elevating means including a boom pivoted at itslower forward end for pivoting about a horizontal axis fixed as to thevehicle, means hanging the grapple from the upper rearward portion ofthe boom, said elevating means and grapple being capable of elevatingthe leading end of an elongate load, characterized by:

power winch on the vehicle, a cable leading therefrom to the lower partof the grapple independently of the means hanging the grapple to dragthe load as the vehicle moves and to adjust the hanging angle of the ppsaid grapple including tongs and a cable tensioned flexible binderintervening between the lower portions of the tongs for tightening aboutthe load in the tongs for skidding the load;

said skidder including powered swiveling means carried by the boom nearits top for swinging the tongs angularly about a generally vertical axisto lie crosswise of the elongate load when the vehicle is not alignedwith the load length; and

control means accessible at the drivers position for controlling theelevating means and tongs and the swiveling means and the winch means.

12. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including elevating means and a grapple hung from the elevatingmeans and which can be lowered by the elevating means for gripping theleading end portion of an elongate load, said elevating means and thegrapple being capable of elevating said leading end, characterized by:

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the grapple independently of elevating means to drag the load asthe vehicle moves, said winch being operable to take slack out of thecable to prevent a swinging back of the hung grapple as the vehiclestarts, and to adjust the hanging angle of the grapple;

said grapple being power actuated for gripping the load and designed todrop the load upon release of the gripping action; and

control means accessible at the drivers position for controlling theelevating means and grapple and the winch means.

13. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including elevating means and a grapple hung from the elevatingmeans and which can be lowered by the elevating means for grip ping theleading end portion of an elongate load, said elevating means and thegrapple being capable of elevating said leading end and said elevatingmeans being a boom pivotable through an angularity substantiallychanging the proximity of the load to the winch, characterized by:'

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the grapple independently of elevating means to drag the load asthe vehicle moves, said winch being operable to take slack out of thecable to prevent a swinging back of the hung grapple as the vehiclestarts, and to adjust the handling angle of the grapple; and

control means accessible at the drivers position for controlling theelevating means and grapple and the winch means.

14. A skidder for elongate loads including a vehicle having a driversposition, and load handling and skidding means carried by the vehicleand including elevating means and a grapple hung from the elevatingmeans and which can be lowered by the elevating means for gripping theleading end portion of an elongate load, said elevating means and thegrapple being capable of elevating said leading end and said elevatingmeans being a boom pivotable through an angularity substantiallychanging the proximity of the load to the winch, characterized by:

power winch means on the vehicle, a cable leading therefrom to the lowerpart of the grapple independently of elevating means to drag the load asthe vehicle moves, said winch being operable to take slack out of thecable to prevent a swinging back of the hung grapple as the vehiclestarts, and to adjust the hanging angle of the grapple; and

control means accessible at the drivers position for controlling theelevating means and grapple and the winch means; said cable beingreadily separable from the hanging grapple for use independently of itin winching a load from an inaccessible point.

(References on following page) References Cited UNITED STATES PATENTSLarson 214653 Westfal1 214523 XR Sandland.

Hollis et a1 294-111 XR Larson.

Woodside et a1.

10 FOREIGN PATENTS 3/1932 France. 2/1966 Germany.

5 ALBERT J. MACKAY, Primary Examiner

